In the related art, there is known a hybrid type construction machine in the field of construction machinery such as a power shovel. In the hybrid type construction machine, electric power is generated by rotating an electric generator using extra output power of an engine or discharge energy of an actuator, the electric power generated by the electric generator is accumulated, and actuation of an actuator is assisted using accumulated electric power. In such a hybrid type construction machine, a fluid pressure pump motor is used. The fluid pressure pump motor includes an assist pump rotationally driven by an electric motor to pump out the hydraulic fluid to assist a main pump to actuate the actuator, and a regenerative motor rotated by the hydraulic fluid reflowing from the actuator to rotationally drive the electric motor.
In JP 2011-127569A, there is disclosed an assist regeneration device including a motor/generator rotationally actuated by electric energy and a regenerative motor that rotationally drives the motor/generator using energy of a hydraulic fluid, and an assist pump rotationally driven by the motor/generator to pump out the hydraulic fluid.